Electric alarm system



Dec. 8, 1964 E. Ml-:lLl

ELECTRIC ALARM SYSTEM Filed April 15, 1963 FIG-I FIG-Z INVENTOR ERNST ME/L/ United tates Patent fifice 3,l60,866 Patented Dec. 8, 1964 3,160,866 ELECTRIC ALARM SYTEM Ernst Meili, Kusnacht, Zurich, Switzerland, assignor to Cerberus G.m.b.I-I., Had-Ragaz, Switzerland Filed Apr. 15, 1963, Ser.. No. 272,928 Claims Priority, application Switzerland, Feb 19, 1957; Jan. 22, 1958 Claims. (Cl. 340-426) This invention relates to alarm'and signalling systems, such as fire alarm systems, and the present application is by way of being a continuation-in-part application of my copending application Ser. No. 715,645 filed Feb. 17., 1958, and entitled Electric Alarm System and now abandoned.

Electric alarm systems for indicating fires and other conditions to be detected are, of course, Well known and in Wide usage. Certain drawbacks, however, have been encountered in connection withV systems of this nature with reference to faulty operation of the systems and unreliability thereof and to lack of speed in being able to locate with precision a detected condition.

The present invention proposes to overcome these drawbacks in fire alarm systems according to the prior art by providing an arrangement wherein the actuation of any individual detection station by a'condition to be detected will bring about actuation of a central control station which, in turn, will provide for a visible, or audible continuous signal at the actuated station. Thus, the actuated stationisignals the central station and the central station signals back to the actuated station and in this manner the precise location of the actuated signal can readily be detected and without any loss of Valuable time.

Still further, the entire system latches in when actuated so that momentary false alarms which, normally cannot be traced to the source give a definite indication of the point of origin thereof.

The present invention also proposes the provision of a detection and alarm system of the nature referred to which is extremely simple to install thus avoiding the complexity and expense that has attended prior art arrangements of this general nature. More specifically, the present invention has a still further object, the provision of a detection and alarm system having the advantageous features referred to above and which is installed in its entirety by a two Wire cable thus enabling original installations to be made inexpensively and conveniently and also enabling any old installations to be readily converted to obtain the benefits of the detection and alarm system according to the present invention.

In conventional alarm and detection systems, a particularly difficult operation is the checking out of the system to make certain that it is in Operating order. This is a job that must be done frequently in order to make sure that the benefits of the detection and alarm system are being realized. A still further object of the present invention is the provision of a detection and alarm system in which the checking out of the system to ascertain the operability thereof can be carried out readily and with accuracy at any time.

Certain systems of the nature referred to involve elements which are destroyed by the condition being detected as, for example, fire detection and alarm systems involving melting wire links and the like. The melting of such a link, of course, requires that the link be replaced in order to put the system back into effective operation. The present invention has as a' still further object the provision of a system which embodies no destructible elements and which can readily be reset whenever desired from the central control station thus providing an arrangement which can be put back into operation substantially instantaneously after the detected condition has been corrected.

By way of general objectives, the present invention has an objective the provision of an electric detection and alarm system which is absolutely safe and reliable.

A still further object of the present invention is the provision of a detection and alarm system in which a plurality of detection stations are grouped together and connected to a central station and wherein easy identification of the actuated one of the detection stations is possible.

A still further object of this invention is the provision of a detection and alarm system in which a visual indicator is arranged in the vicinity of each detector unit and which indicator is actuated upon the detection of the condition to be guarded against and which indicator is kept in indieating condition until the system is reset and while other detection units of the system are in condition to effect an alarm signal in the central unit. i

The foregoing objects as well as still other objects and advantagesof the present invention will become moreV readily apparent upon reference to `the following specification taken in connection with the accompanying drawings wherein:

FIGURE 1 is a schematic view showing the layout of a detection and alarm system according to the present invention, and

FIGURE 2 is a more or less diagrammatic representation of a single detecting station and a centralcontrol station and the two Wire cable leading therebetween.

The general arrangement, according to the present invention, comprises a central control station, a two Wire cable leading therefrom and a plurality of detecting sta-v tions connected between the opposite sides of the two wire cable and located at the particular points where'- conditions are to be detected. A plurality of central stations can be arranged in a group'in a central location and a plurality of two Wire cables can lead therefrom so that the central station, when actuated, will indicate a certain general region where the detected condition has occurred. An observer can then quickly determine which of the detection units has been actuated in this region.

Each detection unit, according to the present invention includes a relay that is normally non-conductive and which is made conductive when the condition to be detected occurs. remains in eonductive condition and a signal is sent therefrom back to the central station and arelay in the central station closes and remains in closed condition. When the relay in the central station closes another voltage source in the central station is connected to the two wire cable and this raises the voltage at the actuated one of the detecting stations to the point that an indieator therein will be energized and give a visible indication. The two relays will remain held in and the indicator will remain in indicating condition until the entire system is reset by opening a switch in the central station.

The central station also includes an alarm device n the form of a signal lamp or an audible signal such as a horn or siren if so desired. The central station may also include an interrupter for periodically causing Vthe indicator lamp at the detector station to dim so that a blinking ,I signal will be had which will be more quickly .noticeable I than a steady signal.

Referring to the drawings now somewhat more in detal, l i

spaced along the corridor by being placed on columns or' When this relay is made conductive itv w p'osts or the like. The cable leads back to a centrallocation Wherein there is a central station 12 containing the voltage source and a relay and also preferably including visual and audible signalling devices which aretripped off by actuation of any of the pertaining detector stations FIGURE 1 also shows that other two Wire cables as at 13 and 14 could be employed, these cables leading to individual central stations 15 and 16, respectively and each cable having connected therebetween detector stations 11 so that as many particular defined regions as desired could be covered by the detection and alarm system of the present invention. p V

The nature of the detection station and the central station is more fully illustrated in FIGURE 2. In FIGURE 2 it will be seen that the detector station 11 comprises a pair of ionization chambers 17 and 18, with the casing of the station 18 being'perforated as indicated by the dotted line 19. The casingsof theionization chambers are` connected with opposite sides of two Wire cable 1G.

The ionization charnbers each contain a weal radioactive substance as is indicated'therein at 20 and 21. Under normal conditionsthe connection 22 extending between the carriers for the radio-active substance 'is'at a potential mid-Way between the potential of the twoV sides of the two Wirecable 10. However, on account of the perforations in [casing 18, the condition to be detected will overcome this condition of balance so that this connector no longer is in a condition of potential mid-way between t that of the opposite sides of cable 10. This condition is taken'advantage of for bringing about firing of a cold cathode Vtube or valve 23 which has one side 24 connected with side a of two wire cable 10 while its other side 25 is' 'connected by way of a resistor 26 with the other side 101) of the two Wire cable. The cold cathode tube comprises a :trigger element 27 connected With Wire 22 'for causing firing of the tube under certain conditions as VWill Turning, now to the central station 12 it willrbe seen v 4 f i Thesystem described above operates as follows:

Under normal conditions, the potential of trigger 27 is insufiicient to cause firing of glow tube 23. However, if, for example, smoke particles enter Chamber 18 via the perforations therein, the current flowing through this Chamber is reduced since the larger smoke particles when ionized by the radio-active substance in Vthe chamber move more slowly in the electric field than ionized air mole- Vcules such as are in Chamber 17'. This changes the potential of trigger 27 so that tube 23 fires and when this tube lires the impedance of the circuit containing source of potential and two wire cablel Ill is reduced and the amount of .current that 'willrthen flow through the circuit will cause relay R tobe Venergized and close its blades.

When blade 37 of relay R closes interrupter .is energized and blade 34 commences to close and open periodically thus periodically connecting second source of'potential 32 to the two Wire cable. The resultant increase in voltage across cable 1% Will bring about ignition of glow tube 28 periodically so that this tube can readily be seen and thus indicate mmediately which of the detection stations has been Vactuated.H

' As mentioned above, relay R could close a blade directly connecting the source of potential 32 to side 1011 of the two Wire cable andin this case the glow tube 28 Would be ignited 'and would stay ignited without flickering or manually opened at which time the entire system will be that there is a first source of potential therein at 30 having one side'connected to said 10a of the `two Wire cable while the other side is connected through `a. normally closed reset switch 31 with one side of the actuating coil of a relay R, the 'other side of which is connected with sidev 10h of the two Wire cable. i

A second source ofv potential 32 in the central station has o ne side connected with) side 10a of two wirevcable 10 while the other side is connected via a resistor 33 with blade 34 of an interrupter device 35.. Blade 34 when closed is effective for connecting the said other ,side of source of potential 32 With side 1012 of the two wire cable andv when open interrupts this connection. A condenser V 36 is also connected between side 10a 'ofthe two Wire cable and the end vof resistor 33 opposite its connection system is employed. 'Closingiof blade 37 of relay R falso';

connects this source of potential to visual indicating means 379, which maybe an electric lamp and' to an audible signalling device 40 Which'may be =a siren or a Vhorn. Relay R may also have other blade nieansione ofrvwhich':

is Vshown artl 49 for effecting further control functions when the system is iactuated. i i

cable could also be elfecteddirectly by a blade'lofv relay R if a blinking signal Vat the detector station VWas not desired and, instead, a steady 'signal was to ybe obtained.

reset and ready for operation in the event of another detected condition =at the same or another detecting station.

` From the foregoing it will be appreciated thatV the system according to the present invention is relatively simple and easy to install Vand certain and safe and reliable in operation and that it meets the following important requirements: 1

i (l) The actuation of a sensing member to cause an optical indicating element to be actuated in the neighborhood of 'the sensing member.

(2) When the optical indicating device associated With the sensing member is illuminated this indicates that the V account of a condition to-be detected or accidentally on V been checked and the system reset.

account'of a false tripping thereof for any reason Will cause the detecting station to'remain activated until it has (5) zThe detection of a condition creates aV visible sig- V n'althat is indicated for a substantial distance and is conspicuous and,` therefore the exact detecting station that has been sactuated can easily be located; V

' .(76) Aisignal is given 'at the central control vstation 1 and an -indication is given at each'and every detecting e station that isactuated.

It'will be evident that the connection of source of potential 32 between sides 10a and ltlbof the two lWire (7)?? In addition to Operating -signals and alarrns, a

relayiisavailable'in the central station which can' control 'furtherfunctions such as turning ofi devices, for sounding, additional alarms, and the like.

(8)V The system according to the present invention is sol arrange'd that it can easily be installed in place of 'older systems without necessitating anyfexpensive and'laboriousV i v change-in the alarm cableV system orznetwo'rk.

It' will alsofbe appreciated'that Vwhile the sensing elements according to the present invention 'have been disclosed as ionization'chambers andthe' relay in the detection station has been shown as a cold cathode glow tube, these individual elements are subject to being replaced by other well known elements. The cold cathode glow tube serves as a relay which latches in and for this reason other latch type relay could be employed. The ionization chambers 'serve as a triggering device for triggering the relay into conductive condition and yit will be evident that other trigger devices could be used, such as bimetallic elements in connection with heat or fire for example, or light sensitive elements for a light condition, or other detectors for various conditions, and that substantially equivalent Operating results would be had.

It will also be evident that in the central station while sources of potential 30 and 32 have been indicated as batteries, with other circuit components alternating current supplies could be used in place of batteries and equivalent results would be had.

It will also be evident that the system of the present invention is particularly useful as a fire alarm system but it can also be employed for detecting other conditions and for use as a burglar alarm and the like merely by selecting a sensing device or sensing element or trigger means for the relay in the detectionstation that is Sensitive to the condition to be detected, such as vibrations or heat or the presence of certain vapors in the atmosphere or the like.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and`accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. An electric alarm system for indicating changes in a predetermined condition at a plurality of different points comprising; a plurality of alarm devices with one thereof located at each of said points, each alarm device including an indicating member pertaining thereto, a control center common to all of said alarm devices, a two wire circuit between which said alarm devices are connected in parallel and which circuit leads to said control center, said control center comprising a relay, a first voltage source and a normally closed switch connected in series between the two sides of said circuit, an alarm element operable in response to closing of said relay, a second voltage source in said control center having one side 6 connected to one side of said circuit, means under the control of said relay and connected to the other side of said circuit and to the other side of said second voltage source and operable upon closing of said relay to connect said other side of said second voltage source to the said other end ofpsaid circuit, each alarm device comprising a sensing member Sensitive to the said condition, each alarm device also comprising a normally non-conductive relay member connected across said circuit and under the control of said sensing member and operable by said sensing member upon the sensing of acondition to be detected to become conductive, each said relayvmember When conductive bringing about a flowof current in said circuit which will actuate said relay in the said control center into closed condition, the indicating member pertaining to each said alarm device becoming operative only upon the connection of said second source of voltage to the circuit upon closing of said relay, and said normally closed switch being operable when opened to interrupt said circuit to halt the fiow of current through said relay and the actuated ones of said relay members thereby to reset the system.

2. An electric alarm system according to claim 1 in which each said relay member is a glow triode.

3. An electric alarm system according to claim 1 in which each said indicatng member is a glow tube.

4. An electric system according to claim 1 in which said sensing member pertaining to each alarm device is in the form of a pair of ionization chambers with one the-reof having a closed casing and the other having la perforated casing.

5. An electric alarm system according to claim 1 in which the control center includes means for periodically varying the voltage supplied to the circuit by said second voltage source to cause periodic variations of the indication given by any indicating member.

References Cited by the Examiner UNITED STATES PATENTS NEIL C. READ, Primary Examiner. 

1. AN ELECTRIC ALARM SYSTEM FOR INDICATING CHANGES IN A PREDETERMINED CONDITION AT A PLURALITY OF DIFFERENT POINTS COMPRISING; A PLURALITY OF ALARM DEVICES WITH ONE THEREOF LOCATED AT EACH OF SAID POINTS, EACH ALARM DEVICE INCLUDING AN INDICATING MEMBER PERTAINING THERETO, A CONTROL CENTER COMMON TO ALL OF SAID ALARM DEVICES, A TWO WIRE CIRCUIT BETWEEN WHICH SAID ALARM DEVICES ARE CONNECTED IN PARALLEL AND WHICH CIRCUIT LEADS TO SAID CONTROL CENTER, SAID CONTROL CENTER COMPRISING A RELAY, A FIRST VOLTAGE SOURCE AND A NORMALLY CLOSED SWITCH CONNECTED IN SERIES BETWEEN THE TWO SIDES OF SAID CIRCUIT, AN ALARM ELEMENT OPERABLE IN RESPONSE TO CLOSING OF SAID RELAY, A SECOND VOLTAGE SOURCE IN SAID CONTROL CENTER HAVING ONE SIDE CONNECTED TO ONE SIDE OF SAID CIRCUIT, MEANS UNDER THE CONTROL OF SAID RELAY AND CONNECTED TO THE OTHER SIDE OF SAID CIRCUIT AND TO THE OTHER SIDE OF SAID SECOND VOLTAGE SOURCE AND OPERABLE UPON CLOSING OF SAID RELAY TO CONNECT SAID OTHER SIDE OF SAID SECOND VOLTAGE SOURCE TO THE SAID OTHER END OF SAID CIRCUIT, EACH ALARM DEVICE COMPRISING A SENSING MEMBER SENSITIVE TO THE SAID CONDITION, EACH ALARM DEVICE ALSO COMPRISING A NORMALLY NON-CONDUCTIVE RELAY MEMBER CONNECTED ACROSS SAID CIRCUIT AND UNDER THE CONTROL OF SAID SENSING MEMBER AND OPERABLE BY SAID SENSING MEMBER UPON THE SENSING OF A CONDITION TO BE DETECTED TO BECOME CONDUCTIVE, EACH SAID RELAY MEMBER WHEN CONDUCTIVE BRINGING ABOUT A FLOW OF CURRENT IN SAID CIRCUIT WHICH WILL ACTUATE SAID RELAY IN THE SAID CONTROL CENTER INTO CLOSED CONDITION, THE INDICATING MEMBER PERTAINING TO EACH SAID ALARM DEVICE BECOMING OPERATIVE ONLY UPON THE CONNECTION OF SAID SECOND SOURCE OF VOLTAGE TO THE CIRCUIT UPON CLOSING OF SAID RELAY, AND SAID NORMALLY CLOSED SWITCH BEING OPERABLE WHEN OPENED TO INTERRUPT SAID CIRCUIT TO HALT THE FLOW OF CURRENT THROUGH SAID RELAY AND THE ACTUATED ONES OF SAID RELAY MEMBERS THEREBY TO RESET THE SYSTEM. 